Brush-holder spring



Sept. 2 1924.

1,506,740 G. M. EATON BRUSH HOLDER SPRING Filed any 24 1921 WITNESSES: [NVENTOR 5M ATTORNEY Patented Sept. 2, 1924.

UNITED STATES PATENT OFFICE.

GEORGE M. EATON, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

BRUSH-HOLD ER SPRING.

Application filed May 24, 1921.

To all whom 2'25 may concern:

Be it known that I, GEORGE M. EATON, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have inrented a new and useful Improvement in Brush-Holder Springs, of which the following is a specification.

My invention relates to brushholders and it has particular relation to means for attaching a brush shunt to the finger spring of a holder.

Heretofore, in devices of this general character, it has been customary to secure a brush shunt between the hammer and the finger spring by means of silver solder, the inner edge of which extended across the finger at right angles thereto. It has been observed that when the brush of such structures becomes partially worn, the finger spring has a tendency to break where the solder terminates.

In analyzing the cause of the trouble, it has been found that the deflection of the spring is more or less localized at the place above mentioned by reason of the fact that it is the termination of the comparatively rigid silver-solder area. After the brush has become worn to any considerable extent, there is a tendency for the pressure between the brush and the hammer to concentrate at a point adjacent to the outer extremity of the finger spring. This results in a slight bending movement that is more or less localized in the vicinity of the inner termination of the solder. It has also been observed that the soldering operation has a tendency to slightly burn the steel of the spring, thereby materially weakening the same.

One of the objects of my invention is to secure a brush shunt to the finger spring in such manner as to distribute the solder and to thereby avoid the line of localized deflection extending across the spring.

Another object of my invention is to so apply the solder as to lengthen the critical Serial No. 472,116.

occurs at the midwidth of the spring in stead of at the edge of the spring.

Referring to the drawing,

Figure 1 is a side elevational view, partially in sect-ion, of a brushholder having a shunt attached to the finger spring thereof in accordance with my invention.

Fig. 2 is a plan view of a finger spring constructed in accordance with my invention.

Fig. 3 is a view, partially in side elevation and partially in longitudinal section, of the structure shown in Fig. 2.

In the accompanying drawings, a brush holder of any preferred form or construction is shown as comprising a main frame 1 having a brushbox 2 at the forward end thereof adapted to receive a carbon brush 8. A finger spring at is suitably mounted upon a pivotal support 5 and is adapted to exert a yieldable downward pressure against the top of the brush 3.

A brush shunt 6 is soldered between a hammer 7 and the extremity of the finger spring 4; and is grounded to the frame 1 in any preferred manner, as at 8. The ex tremity of the finger 4 is preferably pro vided with a depressed portion 9 of substantially V-shape which is adapted to dis tribute the bending strain along lines transverse to the bending axis, thereby avoiding the weakened critical bending point heretofore encountered.

By this method, it will be apparent that the section of the spring adjacent to the solder is so depressed that the bottom is fundamentally stronger.

By reason of the fact that the depressed portion gradually merges into the flat portion of the spring, the deflection thereof is prevented from localizing at any point of the normal spring section, but is more or less distributed along the sides of the V shape depression in a direction diagonal to the edges of the spring.

I claim as my invention:

1. The combination With a spring, of a second member connected to a free end thereof, the points of connection being 5 bounded by a line of greater length than the Width of the spring.

2. The combination With a spring having a stiifening depression near its free end, of,

a second member secured to the spring between the free end thereof and said stiffening depression.

In testimony whereof, I have hereunto subscribed my name this 19th day of May, 1921.

GEORGE BL EATON. 

